With rapid development of network technologies, video conferencing has become the fastest-developing multimedia communication mode. Traditional business and administrative conferences have been transformed into video conferences. A video conference system separately transmits various types of data, such as static and dynamic images, voices, text, and pictures of an individual or a community in two or more different locations, by using existing various electrical communication transmission media, to a computer of each user, so that geographically-dispersed users may exchange information in various manners, such as images and voices, which may serve as a substitution for an onsite conference.
Typically, a camera and a display apparatus are placed in each site. The camera collects an image of a local site and the display apparatus displays images of both the local site and another site. Images are displayed on a per-site basis. Because display space of images for each site is limited and a quantity of attendees in each site is not determinate, it is difficult for a viewer to clearly see a speaker or an intended attendee. Moreover, when a quantity of sites is large, the effect of displaying images from all sites on the same display apparatus is poor.